Industrial automation is the use of machines, sensors and software to run a factory with very few people. Take a soft-drink plant. Machines fill, cap and label thousands of bottles every hour, and a few operators sit in a control room and watch the whole plant on screens.
A plant is controlled in layers. At the bottom are the machines and the sensors that measure them. Beside each machine sits a small computer that reads the sensors and switches the machine on and off. Above these computers is a control room, where operators watch and steer the plant. Together these are the industrial control systems (ICS). The most important products in this layer are the PLC beside each machine and the SCADA software on the operators' screens.
Plants are of two kinds, and the kind decides which controller they use. A plant that makes separate items, such as bottles, scooters or meter casings, is called a discrete plant. It puts a PLC beside each machine. A plant where a liquid or gas keeps moving through pipes and vessels, such as a refinery, a fertiliser plant or a dairy, is called a process plant. A large process plant usually uses a distributed control system. A small one, such as a dairy, often uses PLCs instead. The two kinds buy different products, but both are watched from the same kind of control room.
Above the control room is manufacturing operations. This is the software between the ERP, which decides what the factory should make, and the controllers, which run each machine. It follows every order, every machine and every defective piece. Below it are the machines themselves, described under industrial machinery: motors, pumps, compressors and robots, often built for one industry only. Beside them, quality inspection measures a few parts of each batch in a laboratory and photographs every item on the line.
Two facts shape this whole world. First, factory equipment is rarely replaced. A controller installed today may run for twenty years or more, so makers earn from spare parts and aftermarket services for a very long time. Second, the plant network was once separate from the internet, but now it often is not. So OT and IoT security has become a product of its own.
The people who use these products are the operators in the control room, the maintenance team and the automation engineers who write the controller programs. A plant rarely buys the products one by one. It usually orders a whole control system from a system integrator, which is an engineering company that designs the system and installs it. For a large process plant, the maker of the distributed control system often does this work itself.
Newer software adds predictive maintenance, which warns that a machine is about to fail, and industrial IoT, which sends machine data to other systems. Both depend on the records kept for tracing every batch.